The Dorello Canal

Historical Development, Controversies in Microsurgical Anatomy, and Clinical Implications

Varun R. Kshettry, M.D; Joung H. Lee, M.D; Mario Ammirati M.D., M.B.A


Neurosurg Focus. 2013;34(3):e4 

In This Article

Historical Development

Primo Dorello was born in 1872 in Narni, Italy.[14] He obtained his degree in medicine and surgery in Rome in 1897 and remained there as an Assistant Professor in the Department of Normal Human Anatomy. It was during his stay in Rome that he published his paper, "Considerations on the cause of transient paralysis of the abducent in middle ear inflammation."[13] Dorello described a bony prominence at the petrous apex called the spina sphenoidalis. Just medial to this structure is a depression in the sphenoid bone. The lateral side of the depression contains the petrosphenoidal suture, and the medial side is bounded by the upper outer margin of the lamina quadrangularis (now referred to as the clivus). This depression forms a canal whose superior margin is formed by the ligamentum petrosphenoidale described earlier by Gruber.[18] The ligament runs from the spina sphenoidale to a subtle bony prominence just below the processus clinoidei posticus (posterior clinoid process), which Dorello termed the accessory process of the posterior clinoid.[13,17,37]

The dissections performed by Dorello, prior to the advent of the surgical microscope, revealed that the inferior petrosal sinus and abducent nerve run through this canal. He believed that the canal represents a fixed space in which inflammatory edema can compress the nerve and postulated a vascular mechanism for inflammatory extension to this region in the setting of middle ear infection. Dorello argued that the veins of the tympanic cavity are continuous with the petrosal sinuses and provide a conduit for direct spread of inflammation. He cited the work of Adam Politzer, an Austrian otologist, who described the technique of injecting middle ear veins indirectly through injection of the petrosal and transverse sinuses.[14,28] Although initially disputed by Gradenigo, Dorello's work was affirmed by multiple contemporaries, and Gradenigo later modified his theory to align with the work of Dorello.[5,6,14,17]

Primo Dorello was appointed to the Chair of Human Anatomy at Perugia, Italy, in 1926 and remained there until 1946. His interests were broad and included anthropology and photography. He produced 1674 stereoscopic negatives on glass of Italian architecture and city landscapes.[14] In 1939, he was nominated for the Nobel Prize in Physiology or Medicine (

Although credited with the discovery of this canal, Dorello was not the first to describe it. In 1859, Wenzel Gruber described a fibrous ligament that extends from the petrous apex to the lateral dorsum sellae and creates a canal containing the abducent nerve.[18]